The present invention relates to a rotary machine integral with a control device, and more particularly to a rotary machine and control device combination which comprises a rotary machine such as a pump, a fan, or the like and an operation control device such as an inverter device for controlling the rotational speed of the rotary machine.
It has widely been practiced to combine a rotary machine such as a pump, a fan, or the like with an inverter device for converting the frequency and voltage of a commercial AC power supply into an arbitrary frequency and voltage thereby to control the rotary machine to rotate at a variable speed. Since the inverter device is capable of changing the rotational speed of a motor which actuates the pump or fan, the inverter device can operate the pump or fan at a rotational speed optimum for the load on the pump or fan, and hence can save more energy as compared with operating the pump or fan at a rated speed.
It is known that various water supply apparatus are operated according to a constant pump discharge pressure control process. In the constant pump discharge pressure control process, a pressure sensor is located-at the outlet port of a pump, and a PI controller sends a rotational speed signal to an inverter device in order to equalize a detected signal from the pressure sensor to a pressure setting. The inverter device controls the rotational speed of a pump to control the discharge pressure of the pump at a constant level. It is also known that various water supply apparatus are operated according to a constant estimated terminal discharge pressure control process. In the constant estimated end discharge pressure control process, a target pump discharge pressure is successively changed on the basis of a flow sensor signal or a rotational speed for thereby controlling the water pressure supplied to an end consumer at a constant level.
Furthermore, it is known that air-conditioning systems or the like are operated according to a constant temperature control process. In the constant temperature control process, a temperature sensor is located at the outlet port of a fan, and a PI controller controls an inverter device to control the rotational speed of the fan in order to coincide the temperature of air discharged by the fan with a predetermined temperature setting.
If a variable-speed pump or variable-speed fan which is equipped with such an inverter device is incorporated in a water supply apparatus or an air-conditioning system, then the variable-speed pump or variable-speed fan needs to be operated according to various control processes. For example, if such a variable-speed pump is incorporated in a water supply apparatus, then the variable-speed pump is operated or stopped by an operation or stop command sent from a control station remote from the pump. These operation statuses need to be displayed. For automatically operating the pump to keep the discharge pressure constant, it is necessary to supply a signal from a pressure sensor at the outlet port of the pump to a control device in the water supply apparatus, so that the control device controls the rotational speed of the pump under variable-speed control to keep the discharge pressure constant. When an amount of water to be supplied, which represents a load on the pump, becomes very small, since the pump would otherwise operate in a shut-off mode, it is necessary to store water in a pressure tank connected to the outlet port of the pump and stop the pump.
Therefore, if a variable-speed pump equipped with an inverter device is incorporated in a water supply apparatus, then the water supply apparatus needs an operation control device which generally comprises a CPU and a memory.
Operation control specifications for a water supply apparatus which employs a variable-speed pump vary greatly depending on conditions of the installation site. Therefore, data to be stored in the memory for controlling the operation of the water supply apparatus need to be set depending on facility details at the installation site. Actually, the operation control device requires a CPU and a memory for controlling the inverter device, and a CPU and a memory for controlling the pump. However, it has been difficult to employ a common CPU and a common memory for those CPUs and memories because of the facility details at the installation site. Since the operation control details vary from pump type to pump type and also from operation control condition to operation control condition at the installation site, it is necessary to use memories (ROMs or the like) storing programs suitable for the operation control specifications.
In the water supply apparatus, furthermore, if facilities are to be added or modified to meet demands for an increased amount of water to be supplied, for example, then data stored in the memories need to be changed accordingly. However, it has not been easy to change the data stored in the memories because the control data are stored in the ROMs or the like.
The present invention has been made in view of the above conventional drawbacks. It is an object of the present invention to provide a rotary machine integral with a control device, which is effective to reduce the cost of manufacture of a water supply apparatus or the like employing a variable-speed pump or the like, and allows control programs to be easily established at the installation site.
According to a first aspect of the present invention, there is provided a rotary machine and control device combination which comprises a rotary machine such as a pump, a fan, or the like and a control device integral therewith, the control device comprising an inverter device for operating the rotary machine, a memory for storing a control program for the inverter device and a program for controlling operation of the rotary machine, a CPU operable according to the programs stored in the memory, an input and output unit connected to sensors and switches positioned in said rotary machine, one or more serial ports connected to the CPU, and means for rewriting contents stored in the memory.
The memory may store the control program for the inverter and the program for controlling operation of the rotary machine.
The memory may comprise a flash memory.
The rotary machine and control device combination may comprise a plurality of rotary machines and control devices integral therewith, with the rotary machines having serial ports connected to each other for coordinated operation according to a machine adding and relieving process, an alternate machine operating process, and a failure machine-switching process.
An electronic circuit section including the memory and the CPU of the control device may be encased by molded resin.
With the above rotary machine and control device combination, since the control device has the means for rewriting contents stored in the memory based on a signal entered from the serial port or ports, both a control program for the inverter and an operation program for starting and stopping the rotary machine can be written into the memory. Because only one set of a memory and a CPU, rather than two sets of memories and CPUs that have heretofore been required, is sufficient, the cost of manufacture of the control device is reduced.
Since the memory is associated with the means for rewriting the programs stored therein, the control program can be modified to suit the operating status of the rotary machine at the installation site, and only one set of hardware is needed to provide a water supply apparatus that can be controlled by software to meet demands under various different operating conditions. Therefore, the hardware arrangement can be mass-produced and hence its cost can be lowered. Furthermore, the user of the rotary machine can easily add a pump, for example, to meet a change in the demand for water to be supplied from the water supply apparatus. Therefore, the rotary machine can be made highly flexible for the user.
According to a second aspect of the present invention, there is provided a rotary machine and control device combination which comprises a rotary machine such as a pump, a fan, or the like and a control device integral therewith, the control device comprising an inverter device for operating the rotary machine, a memory for storing a plurality of control programs, a CPU operable according to the programs stored in the memory, an input and output unit connected to sensors and switches positioned outside of the control device, one or more serial ports connected to the CPU, and means for externally selecting a control program to be used among the control programs.
The memory may store a control program for the inverter and a program for controlling operation of the rotary machine.
The rotary machine and control device combination may comprise a plurality of rotary machines and control devices integral therewith, with the rotary machines having serial ports connected to each other for coordinated operation according to a machine adding and relieving process, an alternate machine operating process, and a failure machine-switching process.
An electronic circuit section including the memory and the CPU of the control device may be encased by molded resin.
With the above rotary machine and control device combination, since the control device has the means for selecting a control program to be used among the control programs stored in the memory, and switching programs to operate the CPU with the selected program, it is possible to select a control program most suited to the type of the pump or operating conditions of the installation site. Therefore, pump control devices having a plurality of control programs may be mass-produced in advance, and it is possible to select, at the installation site, a necessary control program to be used among those control programs. Only one set of hardware is needed to provide a water supply apparatus that can be controlled by software to meet demands under various different operating conditions. Therefore, the hardware arrangement can be mass-produced and hence its cost can be lowered. Furthermore, the user of the rotary machine can meet specifications of many types manufactured in small lots at the installation site. Furthermore, the user can easily add a pump, for example, to meet a change in the demand for water to be supplied from the water supply apparatus. Therefore, the rotary machine can be made highly flexible for the user.
According to a third aspect of the present invention, there is provided an inverter device which comprises an inverter section having a power device, a driver circuit for operating the power device, a control circuit including a CPU for controlling the driver circuit, and an interface circuit, the inverter section being mounted on a circuit board, the circuit board with the circuit components thereon being encased by molded resin, with only input and output lines and interface terminals being disposed outside of the molded resin.
The molded resin may accommodate a protective circuit for monitoring an operating status thereof and protecting.
The molded resin may further accommodate a converter section comprising a rectifier, and a rush current prevention circuit.
The inverter device may comprise a converter section comprising a rectifier and a rush current prevention circuit, wherein the converter section is mounted on a circuit board, and the circuit board with the circuit components thereon are encased by molded resin, with only input and output lines disposed outside of the molded resin.
The inverter device may comprise a combination of resin-encased module of the inverter section and a resin-encased module of the converter section, with a capacitor connected between the converter section and the inverter section.
The control circuit may have an electrically rewritable memory for storing a program, the program stored in the electrically rewritable memory being rewritable from outside of the molded resin via the interface circuit.